1. Field of the Invention
This invention relates to a brake apparatus for a shutter for a camera.
2. Related Background Art
A brake apparatus for the shutter blade moving mechanism of a camera according to the prior art is designed such that as shown, for example, in FIG. 7 of Japanese Laid-Open Patent Application No. 61-251830, a brake lever is urged against a washer by the biasing force of a belleville spring, whereby a friction torque is applied. This brake apparatus is also designed such that the pin of the blade moving mechanism bears against the brake lever of the brake apparatus near the end of the blade movement of the blade moving mechanism and a brake is applied to the blade moving mechanism by the friction torque of the brake lever.
In recent years, a requirement for higher speed such as an increase in the maximum shutter time and tuning speed of a shutter has been rising. To satisfy the requirement, it is necessary to increase the movement speed of the blade moving mechanism and as a result, the necessity of securing durability has arisen. In addition, the necessity of strengthening a brake apparatus for stopping the blade moving mechanism has also arisen. However, if as a countermeasure for that, the force of the belleville spring is simply strengthened to thereby increase a friction torque produced, the frictional force between the brake lever and the washer will become great and a mechanical problem such as galling will become more liable to occur in the portion of contact with the belleville spring. This has led to the problem that the durability of the brake itself becomes liable to be spoiled.